Gregory's ServerThis pretty chip from 1981 helped connect an IBM mainframe to data-entry terminals. 1/14
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@kenshirriff awesome to be taken back to those days. Any idea what this board was from? I’ve long since forgotten. @mwkoehler I think those 5120745 chips are 2K static RAMs. So this board is memory, probably cache, maybe for a System/370 computer.  I actually used a 3270 wayback in 1990s I feel quite lucky to have been part of a tiny piece of computing history The server side ran an OS call MVS I think but I'm not sure. - it definitely had pre-TeX typesetting .. roff, troff?  @kenshirriff One question that may sound really stupid but "I really cannot understand", you reverse engineer those IBM chips ... But .. does it mean IBM has lost all the lore about them or they don't want to make it publicly available ? Why ? And if that's the case "why they don't come after you for exposing it ?". I mean it's all super cool, super clever, "tremendous exercise" but does it mean "original documentation is lost forever" ?? 🤔 @gilesgoat That's an interesting question. Companies never expose the full details of their chips. The one exception that I know of is that someone talked Intel into releasing the masks for the 4004 processor: https://4004.com/mcs4-masks-schematics-sim.html  @kenshirriff @gilesgoat There is a story of a Russian chip that obviously reverse engineered a TI chip since the TI logo is on the chip. There is also a story of a RE chip (PDP-11 I think?) with a Russian something to the effect "steal from the best" @kenshirriff Oh yes those early chips were so easy to copy. I once watched someone do that job. |
Mainframes were extremely slow compared to modern computers but they could support rooms full of users. The trick was that mainframes offloaded the text editing to the terminals, while a special "I/O channel processor" pumped data directly into memory without using the CPU. 2/14